Improvement in apparatus for compressing air



UNITED STATES PATENT OFFICEu WILLIAM ARTHUR, OF BROOKLYN, NEW YORK.

IMPROVEMENT IN APPARATUS FOR COMPRESSING AIR.

To all whom it may concern:

Be it known that I, WILLIAM ARTHUR, of Brooklyn, in the county ot' Kingsand State of New York, have invented certain new and useful Improvementsin Apparatus for Compressing Air; and I do hereby declare -that thefollowing is a full, clear, and exact description of my said invention,reference being had to the accompanying drawings, in which- Figure lrepresents a plan of an air-compressing apparatus constructed accordingto my invention. Fig. 2 represents a front elevation of a'portion of thesame; and Fig. 3 represents an elevation ot' another portion of myapparatus.

Difficulty has been experienced in compressing air toa high tension, onaccount of the imperfection of the valves of the pumps employed for thepurpose,the necessity of leaving a space for clearance at the end of theair-pump barrel, and the leakage of the piston-packing, because, as thedifference between the pressures of the air entering the pump and thatleaving it increases by reason of the increase in the tension of thecompressed air, the leakages increase and the expansion of the air leftin the clearance-space at the end of the stroke of the piston issufdcient upon the return-stroke to fill the pump-barrel to aconsiderable extent and greatly diminish the quantity of the air drawnin by the movement of the piston. The diiieulty in compressing air to ahigh tension with an ordinary air-pump is, in fact, so great, as Ihavefound by experiment, that it is practically impossible to ropera-te theair-pump so as to raise the tension ot' the air upon which it acts amuch greater extent than eighty pounds per square inch, without anextravagant expenditure of power, unless the air-pump be constructedwith much greater nicety than is the practice in machine-shops, whichgreatly increases the cost of the apparatus, and unless much greatercareis exercised in keeping it in working order than can be obtained fromthe class of operatives by whom such apparatns is generally worked.

The object ot my invention is to permit air to be compressed to anydesired tension without exceeding a certain predetermined difference ofpressure between the air entering and the air leaving the pump-barrel,so that the air-pump is never required to compress the air upon which itacts more than it; is capable of compressing it advantageously.

To this end my invention consists in compressing the air m ethodicallyby combining the air-pump with two or more air-vessels by means ot'pipes and stop-cocks or valves, in such manner that the air compressedinto one air-vessel maybe used to supply the pump when compressing airinto one or more other air-vessels to ahigher tension. The air enteringthe pumpbarrel is therefore already compressed to a certain tension, andth'e amount of increase in tension which the pump is required to produceneed not exceed that at which it will work advantageously.

. Myinvention consists, further, in constructing the vessel into whichthe air is ultimately compressed ot' conical form and combining it witha water force-pump, so that the air may be compressed into the smallestpart ot' the vessel by the action of the water injected into the vessel.

rlhe air-compressing apparatus represented in the accompanying drawingsis an illustration ot' one mode in which my invention may be embodied,and is suitable for compressing air for the purpose of blowing out thepipes of petroleum-wells. The air-pump A used in this example is anordinary double-actin g air-pum p iitted with puppet-valves andair-passages, which are contained in a chest, H, above the pump-barrel.

' The suction air-passages` leading to the entry-valves ot' the pump arefitted with short pipes, to which stop-cocks G G are applied, so thatthe entry-valves may be supplied with air from the atmosphere, or may beshut oft' therefrom by closing the stop-cocks. The suction air-passagesot' the pump are also connected by a pipe, I, with four oftheair-vessels, B' B2 B3 B4, all of which are plain cylinders, while thefifth, B, is of conical form.

The branch pipe leading from the main suction-pipe to each air-vessel isfitted with a stopcock, Ff F2 F3 F4, by means ot' which the airvessel towhich it appertains may be connected with the suction-pipe of the pump,or may be disconnected therefrom. The discharge air-passage leadin gfromthe exit-valves ofthe air-pump is also connected with the air vessels bymeans of a pipe, J, and the branchI pipe leading from thisdischarge-pipe to each ot' the air-vessels is fitted with a stop-cock, DD D2 D3 D4, by means of which any one of the vessels may be put inconnection with the discharge-pipe of the pump, or maybe disconnectedtherefrom. For a reason that will be hereinafter stated, a seconddischarge-pipe, J f, may be used to connect the last air-vessel in theseries with the discharge-passage of the pump. The conical air-vessel Bis also connected by means ot' a pipe, K, with a forcepump, L, suitablefoi-'injecting Water into it; and as this pump is used to inject waterinto the air-vessel when the'air within it has previously beencompressed to a high tension, the area of the pump-plunger should besmall enough to enable the motor employed to operate it with ease underthe highest tension to which the air is to be compressed.

The main suction-pipe I, the two discharge- I pipes J J, and theinjection-pipe of the water force-pump are cach tted with a stop-cock, EC M N, between the air-vessels and the pumpvalves. The conicalair-vessel is fitted with an exit-pipe, P, leading from its upper end tothe place Where the compressed air is to be used, and this pipeisttedwith a stop-cock,R.

The mode ofioperation with such an apparatus is as follows, assumingthat the operation is commenced when the air-vessels ot' the apparatusare filled with air at the pressure of the atmosphere: The stop-cock Eofthe main suction-pipe I, and those F F2 F3 F4 of all the branchsuction-pipes are closed the stopcoek N of the water injectionpipe,andthatM of the supplementary-discharge pipe J are also closed thestop-cock C of the main dischargepipe J, and those D D D2 D3 D4 of allthe branch discharge-pipes are opened, and the stop-cock R of theexit-pipe l? is closed; the stop-cocks Gr G, which connect thesuctionpassages of the air-pump with the atmosphere are opened. Theair-pump is then set to work and air is drawn into it from theatmosphere through the entry valves and discharged through theeXit-valvesinto the main dischargepipe J, whence it passes into al1 theair-vessels. As the pump operates, and barrelful after barrelful of airis forced into the air-vessel, the tension of the air therein isprogressvely raised, and the operation of the pump is continued untilthe pressure in all the air-vessels reaches the limit at which it isexpedient to work the air-pump-say eighty pounds per square inch. Theentry air stop-cocks Gr G at the suction-passage of the pump are thenclosed, so as to shut off the connection of the pump with theatmosphere. The stop-cock D4 of the branch discharge-pipe leading to thelast air-vessel, B4, is closed, and the stop-cock E of the mainsuction-pipe I and that F4 of the brauch leading to the last air-vessslB4 are opened. By these operations the suctionpassages of the p ump areput in connection with the last air-vessel in the series, so that thesupply for the pump is drawn from this airvessel, in which the air hasalready been compressed to a tension of eighty pounds per square inch.The air-pump then operates upon this compressed air and forces it intothe remaining air-vessels of the series, and as the work imposed on thepump and the strain incident thereto is to overcome the differencebetween the pressure of the compressed air entering it from the vesselB4 and that in the remaining air-vessels into which the air isdischarged, the air may be compressed in thelatter to a much greatertension than eighty pounds per square inch above that of the atmospherebefore the strain upon the pump reaches the working-pressure ot eightypounds per square inch. Moreover, as the lealrages at the valves and theexpansion of the air in theclearauces ofthe` pump-barrel depend upon.the difference between the pressure of the air entering and ofthatleaving the air-pump, they will not be more injurious undertheincreased tension in the remaining air-vessels than they were when theair drawn from the atmosphere was rst compressed to the tension ofeighty pounds per square inch. Vhen the difference between thevpressures of the air in the lastair-vessel, B4, and the remainingair-vessels amounts to the predetermined quantity oi' eighty pounds perinch,the last air-vessel, B4, is disconnected from the pump by closingthe branch suction stop-cock F4, and the last airvessel, B3, of thoseremaining is disconnected from the others, and is put in connection withthe entry-valves of the pump by closing and opening the properstop-cocks. The operation ofthe pumps is then continued until thedifference between the pressure of the air remaining in it and thatforced into the other vessels reaches eighty pounds per square inch, asbefore, when that second vessel is shut oft' from the pump, and thesupply of the'J pump is drawn from the third vessel of the set, Whichthen becomes the last of the series in connection with the pump.

The operation is carried on until the fth vessel, B, alone receives thecompressed air from the pump, and the pressure of the air in it exceedsby eighty pounds per square inch the pressure in the fourth vessel. Thenthe connection with the fifth vessel and the airpump is shut off 'byclosing the stop-cock D, and the compressed air may be permitted toissue through the exit-pipe to the place where it is to act. If,however, a still greater pressure be required, the force-pump L is setto Work to inject water into the lower end of the fifth vessel, and thewater thus injected, being practically incompressible, compresses theair into the upper part of the fth air-vessel. The compression thusexerted may be carried as far as the strength of the apparatusV and thepower of the motor will permit.

After the compressed air has been used, the last vessel in the seriesmight be charged by a repetition of the preceding operations; but,

as the air in each air-vessel is at a different tension, I prefer tocommence charging the last vessel, B4, through the supplementarydischarge-pipe J' with air compressed from the atmosphere, and as soonas the tension of the air in that vessel reaches the tension of the airin the next vessel to open the communication between the two. Byproceeding with all the vessels n this manner the loss of the pressuregained at a preceding operation is avoided.

vIn the apparatus thus described the firstfour air-vessels arerepresented as of the same size; but I propose to make the vessels ofprogressively-larger dimensions from the first, or that receiving themost compressed air,- to the last, as the supply ot' the pump maythereby be kept up longer from the last vessel ot' the series before thedi'erence in pressures between the air entering and leaving the pumpamounts to the predetermined working-press ure in the pump.

The invention is not limited to the number of air-vessels in the series,provided there he at least two, as the number may be increased ordiminished, according to the ultimate pressure required and the highestworking-press ure at which the air-pump is to be operated. So, also, theinvention is not limited to any particular form of the air-vessels; butwhen the water-force pump is used in connection with the last vessel itshould be of conical form, or the sectional areaof the upper end of thatvessel should be less than that ot its lower end.

The apparatus may be employed to compress gases other than atmosphericair, in which case the air-pump must be first supplied with the gas byconnecting its suction-passages with the reservoir of gas. So, also, theliquid used to increase-thecompression in the last vessel need notnecessarily be water, but may be any liquid'which is suited to thepurpose.

What I claim as my invention, and desire to secure by Letters Patent,is-

1. The combination of the airpump employed to compress air with a seriesof air-vessels by means of pipes and stop-cocks connecting the air-pu mpand air-vessels, substantially as hereinbet'ore set i'orth, in suchmanner that the air which has been compressed into one air-vessel may beused to supply the air-pump when compressing the air to a greater extentin another air-vessel, substantially 'as herein set forth.

2. The combination of the said apparatus with a water-force pump, toincrease the pressure of the air in the last vessel, substantially asherein set forth.

3. The conical construction of the vessel of the series into which theair is ultimately compressed, when such vessel is combined with awater-force pump, substantially as set forth.

In witness whereof 1 have 'hereunto set my hand this 17 th day ot'December, A. D. 1864.

WILLM. ARTHUR.

Witnesses:

GHAs. E. Faosr. RIcHD. B. DUvcKINcK, Jr.,

